Organic Light Emitting Diode (OLED) devices emit light autonomously through organic layers, do not need backlights and do not need to be in display by the optical characteristics of liquid crystals, so OLED devices have a faster response time, a greater viewing angle, higher contrast, a lighter weight and a lower power consumption, and are considered to be the most promising flat panel display devices.
When the OLED device operates, electrons are injected from a cathode to a transporting layer. To increase the number of injected carriers and to improve the luminous efficiency, the material used for the cathode of the OLED has an approximate work function to the light-emitting layer to reduce the energy barrier, and the low work function metals such as magnesium, aluminum and silver are all active materials which are prone to react with water and oxygen in the environment, thereby rendering the device dysfunctional. Besides, the hole transporting layer and the electron transporting layer of the OLED device are easily corroded by water and oxygen, and thus the pixels are damaged and the service life of the device is shortened.